Web Forms :: Get The Value User Type In TextBox Of The Listview?

I'm now facing a problem with the listview, on my web form, I have a listview with a textbox at the end of each row, a Submit button, I bind my listview datasource to a table in my database via LINQ, (name Daily Money), here I want that when I click on Submit button, I want to retrieve the text that user typed in the textbox of each row, I tried many ways but it just give me an empty string (the value that was bind to the text on pageload) (first I didn't bind anything to the textbox, second I bind it to a column of the table but all failed).

I used item.FindControl, but it didn't work, how can I retrieve the textbox's value that user typed in (using foreach), or a way to update the listview datasource, I want to insert, update those textbox's value to my database,

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My ItemTemplate:

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